1. Field of the Invention
The present invention relates to a light weight, high performance vibration-damping system. More specifically, the present invention relates to a light weight, elastomeric, butyl, mastic composition which when laminated to a film, provides superior damping properties.
2. Description of Related Art
There is an ever growing need to produce efficient and effective structures. This need, coupled with a desire and increasing demand to conserve energy has created light weight structures that move and/or vibrate at faster speeds, producing higher temperatures and thus creating higher acoustics and undesirably higher levels of vibration. This in turn has necessitated the search for better vibration-damping materials.
It has been known that component parts in devices and structures that vibrate under the influence of an applied internal or external force can be substantially reduced by attaching a layer of viscoelastic material to them. For example, U.S. Pat. No. 3,640,836 discloses a vibration-damping laminate in which the viscoelastic layer is a polymer comprised of ethylene, vinyl acetate and acrylic and/or methacrylic acid. U.S. Pat. No. 3,847,726 discloses yet another viscoelastic adhesive composition of a polyepoxide, a polyether amine, a hetrocyclic amine and a phenol useful as vibration-damping material over a -25.degree. C. to +60.degree. C. range. These compositions disclosed, however, are not effective for vibration-damping over prolonged periods of time and do not provide the required light weight, high performance systems that are desired in this technological age.
The use of rubbers in a composition for the purpose of vibration-damping is also known in the art. JP 90-306255 discloses vibration-dampers and sound insulators containing (a) 100 parts composition containing SBR 25-40, mineral oil 15-40 and carbon black 30-47%, (b) .ltoreq.100 parts (reclaimed ) rubbers (c) 100-600 parts (based on 100 parts a+b) inorganic compounds with specific gravity .gtoreq.2.5, and (d) 10-100 parts (based on a+b) fine powdered coal. EP 335642 A2 teaches laminated composites suitable for vibration-damping that are manufactured from layers of metal or alloy for support, rubber or a viscoelastic polymer for damping, and hot-melt adhesive for bonding. The laminate structure is useful for improved sound-proofing applications. JP 61005158 B4 discloses sound-insulating and vibration-damping materials having specific gravity &gt;2.5 which are prepared by uniting mixtures of 100 parts rubber with 150-600 parts non-metallic fibers and/or nonmetallic scaly inorganic substances such as asbestos and mica with metal fibers. These compositions, however, again do not provide the light weight, high performance, damping effect necessary for the structures in which the present invention finds use.
There is therefore, generally, a need for a high performance, light weight vibration-damping system that allows the industry, especially the automotive industry, to continue to avail itself of technology that produces lighter and lighter cars. Further, there is a need for a high performance system which will tolerate the temperature ranges of from about 0.degree. C. to about 60.degree. C., yet retaining a high sound damping effect.